The building industry currently employs a time-consuming and inefficient method of constructing exterior walls for residential and certain commercial buildings. Usually side walls are constructed by building a frame using lumber, nominally 2".times.4" in dimension, and then attaching one or more let-in braces across the upright frame components ("studs"), which have been spaced usually at between 16 or 24 inch intervals, to improve racking strength and therefore dimensional stability, particularly at corners. Alternatively, a sheet of plywood, oriented strandboard, or other material is attached to the 2".times.4" frame studs at the corners to provide the necessary racking strength. Insulation, e.g., glass fiber batts or foamed polymeric panels, may be applied between the 2".times.4" frame components and then a vapor barrier consisting of a sheet of polyethylene or the like may be applied surrounding the exposed insulation surfaces. Next a "sheathing", such as a foamed polymeric material, cellulosic board, or oriented strandboard, is applied exterior to the outer vapor barrier (which is commonly called the "weather barrier") and then siding of some type (e.g., wooden clapboard, lapboard, or shingles, or profiled vinyl or aluminum siding, etc.) is applied on the outermost surface. Sheetrock may then be applied on the inner surface of the construction to finish the interior walls. Thus, a typically constructed wall for a wood frame (so-called "stick-built") dwelling or commercial building has about 6 layers (from inside to outside): sheetrock, vapor barrier, 2".times.4" frame components including let-in braces or plywood sheets added for racking strength interspersed with insulation, weather barrier, sheathing, and external siding.
Thus, there are an average of eight or more steps needed to construct a wall including both interior and exterior portions. This multitude of steps is costly and requires significant challenges to the builder to keep inventory on hand, to protect the inventory from theft, and to protect partially completed side walls from vandalism and degradation by weather. It is therefore be desirable in the art to enable builders to construct walls more efficiently and with fewer costly risks.
One means of approaching this problem has been the development of "sandwich panels". These panels are frequently of the type used in constructing "pre-fabricated" homes, and typically include an insulative core, such as a rigid polyurethane or polystyrene foam, between cover sheets made of, e.g., thin metal, wood, steel, polyester, ABS and the like. Thus, these panels generally relocate one or more construction steps from the building site to the manufacturer's site, such that a portion of the wall is "pre-fabricated" before reaching the builder. Depending upon the application, the sandwich panel may be suitably load-bearing or not. In some cases the panels can be applied to a wooden frame, and in some cases panels may be interlocked to provide structural form and integrity.